Whether recovering a lost history or charting a new land, scholars and explorers alike often hit at frontiers not only of place, but also knowledge. When the evidence only goes so far, what is the right way to advance? The answer is to make a conjecture: an educated guess that discourses on what is likely the case. Historical examples range from Italian humanists stealing manuscripts from monasteries and reconstructing classical languages, to Jesuit missionaries speculating about land bridges to the Americas, and even Renaissance magicians pioneering in alchemy and astrology. This collective practice is called “conjectural history,” and its roots go far back. But how far back? To answer that question, as we continue Season 6, I have as our guest, Professor Anthony Grafton. A former president of the American Historical Association, and the Emeritus Henry Putnam University Professor of History at Princeton University, Grafton is a scholar of early modern Europe and written history, a frequent contributor to the New York Review of Books and London Review of Books, and the author of many books such as The Footnote (1997) and Magus (2023). Today, we will discuss his current project on “conjectural history.” We discuss the use of conjectural versus counterfactual history, its founders in Herodotus and Thucydides, and proponents like the explorer Jose de Acosta, S.J. and the scholar Lorenzo Valla. Also discussed are Hobbes, Locke, and Rousseau, the birth of modern science from renaissance magic, C.S. Lewis’ The Discarded Image, recent scholarship on premodern eyewitness testimony to the supernatural, the magician Henry Cornelius Agrippa, and the best lost spots of Princeton University. Hosted by Ryan Shinkel, Madison’s Notes is the podcast of Princeton University’s James Madison Program in American Ideals and Institutions. The transcript for this interview is available on the JMP substack page, “Madison’s Footnotes. Chapter Headings: 00:00 | Introduction & What is Conjectural History 4:30 | The Scottish Enlightenment vs. the Renaissance Tradition 11:42 | Conjectural History & a Case Study: Jose de Acosta 19:30 | Theology, Science & The Renaissance 26:19 | Lorenzo Valla and the Donation of Constantine 38:19 | Conjecture, Divination, and Magic Closing | Reflections: History, Belief, and Closing Thoughts Learn more about your ad choices. Visit megaphone.fm/adchoices Support our show by becoming a premium member! https://newbooksnetwork.supportingcast.fm/new-books-network